Use of overbank sediments as a sampling medium in geochemical mapping.
An excursion was arranged in Norway 10.-14. September 1987 in order to study the use of overbank sediments as a sampling medium in geochemical mapping. The conclusions of the excursion are: Overbank sediments (o.s.) are composite samples that represent large drainage areas and can be collected at widely scattered sample sites at low cost. O.s. are transported physicallyin water suspension and are less influenced by chemical processes than stream sediments, which may have coatings of secondary minerals. O.s. collected at shallow depths may reflect anthropogenic pollution, while o.s. taken at depth may reflect natural conditions. Sampling and analysis of overbank sediments have been successfully applied in Norway and we recommend that an excursion is arranged in France and Western Germany in order to evaluate their use in geochemical mapping in other areas of Western Europe.